AstraZeneca Vaccine Booster Shot Produces Strong Immune Response

A third shot of AstraZeneca’s COVID-19 vaccine used as a booster prompts a strong immune response, including against variant strains of the SARS-CoV-2 virus, Oxford University researchers reported yesterday.

But it is not clear that a booster is needed at this time to protect against the variant strains because the period of efficacy of a first and second shot appears to be longer than previously believed, according to a preprint of a report in The Lancet.

The Oxford-led study found that the vaccine’s 76 percent efficacy was sustained for at least 90 days after just one dose and that a second dose can be given after 45 weeks and deliver an improved immune response.

The latest findings offer some assurance of efficacy of a booster should a third shot of the adenovirus-based vaccine be needed to protect against new variant strains.

A separate Oxford University study found that one shot of the AstraZeneca vaccine followed by a Pfizer vaccine booster shot was almost as potent as two doses of the Pfizer vaccine.

Access the two study reports here: bit.ly/3h1PR4x, bit.ly/3w3BnFB. — Daphne Butas